Making touch fasteners of multiple resins

ABSTRACT

Touch fasteners with different portions having different material properties, and methods and apparatus for making such a product. In one embodiment, the fastener includes a cross-linkable polymer, and a first portion of the fastener is cross-linked and a second portion of the fastener is not cross-linked or is cross-linked to a degree less than said first portion. In another embodiment, the fastener is made in a continuous process on a rotating mold roll having a plurality of fastener element mold cavities extending into the mold roll from its outer circumferential surface. The method includes applying a first polymer to the mold roll and forcing some of the first polymer into the mold cavities, with some of the first polymer remaining on the surface of the mold roll in the form of a film having thickness; with a doctoring blade, removing at least some of the first polymer remaining on the surface of the mold roll to at least reduce the thickness of the film of the first polymer on the mold roll surface (in some cases, substantially all of the polymer on the mold roll surface is removed); and applying a second polymer to the mold roll, the second polymer being compatible with, and adhering to, the first polymer.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to fasteners, in particular to hookand loop type fasteners.

[0002] Arrays of molded male fastener elements, e.g., hooks, are oftenformed integrally with a sheet-form base, to provide a sheet-formfastener component. This component can then be engaged with a similarcomponent of female fastener elements to form a “hook and loop”fastener. It is desirable that the fastener elements have good strengthand toughness, so as to provide strong engagement during repeated use ofthe fastener. It is, on the other hand, desirable that the sheet-formbase be relatively soft and flexible, e.g., to allow the base to flexwith a fabric article to which it is attached and to prevent the edgesof the sheet-form component from causing discomfort to a wearer.

SUMMARY OF THE INVENTION

[0003] The invention features an improved, continuously formed touchfastener product with different portions having different materialproperties, and methods and apparatus for making such a product.

[0004] The invention can provide a fastener having both relatively hard,durable regions and relatively softer, more flexible regions. In oneaspect of the invention, such a fastener product is produced by forming,from a cross-linkable polymer, a plurality of molded fastener elementsintegral with a sheet-form base, and selectively cross-linking regionsof the polymer to form the hard, durable regions. The regions that arenot cross-linked remain relatively soft and flexible. In another aspectof the invention, such a fastener is produced by forming the hard,durable regions from a first polymer, and joining to the first polymer asecond polymer having properties different from the first polymer toform the relatively softer, more flexible regions.

[0005] In one aspect of the invention, the invention features a fastenerincluding a sheet-form base member, and, extending outwardly from, andintegral with, the base member, a plurality of molded fastener elements.At least a portion of the fastener includes a cross-linkable polymer,and a first portion of the fastener is cross-linked and a second portionof the fastener is not cross-linked or is cross-linked to a degree lessthan the first portion.

[0006] Preferred embodiments include one or more of the followingfeatures. At least some of the fastener elements are cross-linked. Thebase member is not cross-linked. The fastener elements include across-linkable polymer and the base member includes a non-cross-linkablepolymer, or, alternatively, both the fastener elements and the baseinclude a cross-linkable polymer. The base member has a flexural modulusof less than about 80,000 pounds per square inch (psi), more preferably10,000 to 60,000 psi, and the fastener elements have a flexural modulusof greater than 80,000 psi, more preferably 80,000 to 120,000 psi. Thefastener elements have a flexural modulus that is at least 25% higherthan that of the base member, more preferably at least 50% higher. Thebase has a thickness of less than 0.015 inch, more preferably about0.001 to 0.005 inch. The cross-linkable polymer is selected from thegroup consisting of polyvinyl chloride (PVC), polyvinylidene fluoride(PVDF), poly(ethylene terephthalate) (PET), polyacrylates, polyamides,thermoplastic elastomers, and mixtures thereof. At least some of thefastener elements are male fastener elements, e.g., hooks. The hooks arecross-linked.

[0007] According to another aspect, the invention features a method ofmaking a fastener including (a) forming a fastener comprising asheet-form base member and a plurality of molded fastener elementsextending outwardly from and integral with said sheet-form base member,at least a portion of the fastener being formed from a cross-linkablepolymer; and (b) cross-linking the cross-linkable polymer in a manner sothat a first portion of the fastener is cross-linked while a secondportion of the fastener remains non-cross-linked or is cross-linked to alesser degree than the first portion.

[0008] Preferred embodiments include one or more of the followingfeatures. Step (b) is performed using electron beam radiation. Thecross-linkable polymer is a thermoplastic elastomer that is capable ofincreasing at least 25% in flexural modulus upon substantially completecross-linking. The fastener is formed entirely of a thermoplasticelastomer. The fastener elements are hooks. The hooks are cross-linkedduring step (b). At least a portion of the base is not cross-linkedduring step (b).

[0009] In yet another aspect, the invention features a method of makinga fastener including (a) forming a fastener comprising a sheet-form basemember and a plurality of molded fastener elements extending outwardlyfrom and integral with said sheet-form base member, by forming a firstportion of the fastener from a cross-linkable polymer, and joining thefirst portion to a second portion of the fastener that is formed from asecond polymer; and (b) at least partially cross-linking the firstcross-linkable polymer. The invention further features fasteners made bythis method.

[0010] According to another aspect of the invention, the inventionfeatures a method of making a continuous fastener product having anarray of fastener elements extending from a sheet-form base. The methodincludes: (a) providing a mold roll defining a plurality of fastenerelement mold cavities extending into the mold roll from the outercircumferential surface of the mold roll; (b) applying a first polymerto a surface of the mold roll and forcing some of the first polymer intothe mold cavities, with some of the first polymer remaining on thesurface of the mold roll in the form of a film having thickness; (c)with a doctoring blade, removing at least some of the first polymerremaining on the surface of the mold roll after step (b) from thesurface of the mold roll to at least reduce the thickness of the film ofthe first polymer on the mold roll surface; (d) applying a secondpolymer to the mold roll, the second polymer being compatible with thefirst polymer and adhering thereto; (e) solidifying the first polymer inthe mold cavities to form fastener elements; and (f) removing thefastener elements from the mold cavities.

[0011] Preferred implementations of the method include one or more ofthe following features. In step (c), substantially all of the firstpolymer that remains on the mold roll after step (b) is removed by thedoctoring blade. The first polymer is applied by an extruder. The secondpolymer is applied by an extruder. The first polymer is cross-linkableand the method includes cross-linking the first polymer after removalfrom the mold roll. The first polymer is relatively harder than thesecond polymer. The second polymer is more elastic, when solidified,than the first polymer. The method includes, after step (d), bonding athird polymer to the second polymer.

[0012] According to another aspect of the invention, the inventionfeatures a method of making a continuous fastener product having anarray of fastener elements extending from a sheet-form base. The methodincludes: (a) providing a mold roll defining a plurality of fastenerelement mold cavities extending into the mold roll from the outercircumferential surface of the mold roll; (b) applying a first polymerto the surface of the mold roll and forcing some of the first polymerinto the mold cavities, with some of the first polymer remaining on thesurface of the mold roll in the form of a film having thickness; (c)with a doctoring blade, removing at least some of the first polymerremaining on the surface of the mold roll after step (b) from thesurface of the mold roll to at least reduce the thickness of the film ofthe first polymer on the mold roll surface; (d) applying a tie layer tothe mold roll, the tie layer being compatible with and adhering to thefirst polymer; and (e) applying a second polymer to the tie layer.

[0013] Preferred implementations of the method include one or more ofthe following features. The first and second polymers are differentmaterials. The tie layer comprises an adhesive. The tie layer comprisesa polymer.

[0014] The present invention can provide a fastener having bothrelatively hard, durable regions and relatively softer, more flexibleregions. The inventor has found that such a fastener can be provided byforming, from a cross-linkable polymer, a plurality of molded fastenerelements integral with a sheet-form base, and selectively cross-linkingregions of the polymer to form the hard, durable regions. The regionsthat are not cross-linked remain relatively soft and flexible.Alternatively, such a fastener can be provided by forming the hard,durable regions from a first polymer, and joining to the first polymer asecond polymer having properties different from the first polymer toform the relatively softer, more flexible regions.

[0015] Advantageously, the hard and soft regions can be positioned asdesired to suit a particular application. Thus, in certain cases whereit is desired that the fastener elements be relatively stiff anddurable, while the base be soft and flexible, the fastener elements arecross-linked to a desired degree while the base is not cross-linked oris cross-linked to a lesser degree than the cross-linking of thefastener elements. Alternatively, the fastener elements can be formed ofa first, relatively hard polymer, and the base from a second, relativelysoft polymer.

[0016] Certain aspects of the invention also enable the formation offastener products having relatively stretchable (i.e., rubbery orelastic) bases and relatively stiff or rigid fastener elements. Suchproducts are useful, for instance, in diaper closures, where theelasticity of the base can help to maintain an engagement shear force onthe fastener elements.

[0017] Other features and advantages of the invention will be apparentfrom the drawings, the following description, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a side cross-sectional view of a fastener according toone embodiment of the invention.

[0019]FIG. 2 is a diagrammatic view of a process for making the fastenerof FIG. 1.

[0020]FIG. 2A is an enlarged diagrammatic view of the portion of theprocess of FIG. 2 shown in box A.

[0021]FIG. 3 is a diagrammatic view of an alternative process for makingthe fastener of FIG. 1.

[0022]FIG. 4 is a diagrammatic view of a process for making fastenersaccording to an alternative embodiment of the invention.

[0023]FIGS. 5-5D are cross-sectional side views of fasteners accordingto alternative embodiments of the invention.

[0024]FIGS. 6 and 7 are diagrammatic views of alternative processes formaking fasteners of the invention.

DESCRIPTION OF EMBODIMENTS

[0025] Referring to FIG. 1, fastener 10 includes a plurality of hooks 12that are integral with, and extend from, a sheet-form base 14. The hooksand base may be formed from the same cross-linkable polymer or,alternatively, may be formed of different polymers. If they are formedfrom different polymers the hook-forming polymer is cross-linkable; theother polymer can be either cross-linkable or non-cross-linkable. Hooks12 are cross-linked, while the base 14 is not cross-linked or iscross-linked to a lesser degree than the hooks. As a result, the hooksare tough and durable, while the base is soft and flexible.

[0026] The base should be sufficiently strong to withstand its intendeduse without tearing or other damage, while also being relatively thinand flexible, to give good “drape”. Preferably, the base is less than0.005 inch thick, more preferably from about 0.001 to 0.003 inch thick.

[0027] The hooks have a significantly higher flexural modulus than thebase, preferably at least 25% higher and more preferably at least 50%higher.

[0028]FIG. 2 illustrates a suitable process for forming the fastenershown in FIG. 1. As shown in FIG. 2, a cross-linkable polymer 16 isextruded by extruder 18 onto a roll 19 having hook forming cavities 20(e.g., as described in U.S. Pat. No. 4,872,243, the disclosure of whichis incorporated herein), forming hooks 21 extending from a base 22. Itis noted that this step is shown merely as an example, and can bereplaced by any desired method of molding hooks on a base, e.g., theprocesses described in U.S. Pat. Nos. 4,894,060, 4,794,028 and5,441,687, the disclosures of which are incorporated by referenceherein.

[0029] The resulting hook-carrying base 22 then passes to across-linking station A, shown in further detail in FIG. 2A. Atcross-linking station A, the base 22 passes through a bath of an inertshielding fluid 24, e.g., a solution of salts of heavy metals such asbarium, or a cooled bath of liquid mercury, while the hooks 21 remainabove the surface 26 of the fluid. While the base 22 is in the bath, thehooks are exposed to radiation (arrows E), e.g., electron beamradiation, causing the hooks to cross-link or partially cross-link. Ifit is desired that the base of the hooks remain flexible, the hooks canbe partially submerged in the bath along with the base.

[0030] An alternative process is shown in FIG. 3. In this process, thebath of shielding fluid is omitted, and instead the hook-carrying base22 passes through a series of rolls 28, 30, 32. The arrangement of therolls causes the base 22 to bend around rolls 28 and 32, forming bentareas. Electron beams E1, E2, that point in the machine direction (inthe plane of the page, in FIG. 3), are then directed at the bent areas.Thus, the electron beams will cross-link the hooks without significantlyaffecting the base. If desired, more rolls can be provided downstream ofroll 32, in a similar arrangement, to provide more bent areas at whichradiation can be directed.

[0031] Polymers that are suitable for use in this embodiment of theinvention are those that can be molded to form fastener elements and cansubsequently be selectively cross-linked, as described above. Suitablepolymers include polyvinyl chloride (PVC), polyvinylidene fluoride(PVDF), poly(ethylene terephthalate) (PET), polyacrylates, polyamides,thermoplastic elastomers, e.g., HYTREL elastomers and PEBAX elastomers,and mixtures thereof. Polyester-based thermoplastic elastomers, e.g.,HYTREL elastomers, and polyether/polyamide-based thermoplasticelastomers, e.g., PEBAX elastomers, are preferred. Many of thesepolymers will require suitable cross-linking agents in order tocross-link when exposed to radiation. Suitable cross-linking agents arewell known to those skilled in the art. Suitable polymers that containelectron beam cross-linking agents include thermoplastic elastomersavailable from Zylon Corp., Monsey, N.Y. 10952, under the trade name“ZYLON EBXL TPE”. The cross-linkable polymer can also include additivessuch as fillers, stabilizers, accelerators, and the like, as is wellknown.

[0032] Cross-linking can be effected using various techniques, e.g.,electron beam or ultraviolet radiation, heat, or any other desiredtechnique suitable for the selected polymer. The cross-linkingconditions are selected based on the polymer used and the propertiesdesired.

[0033] In alternative embodiments, a first polymer is used to form thehooks and a second polymer is used to form the base. Thus, thehook-forming polymer can be cross-linkable and the base-forming polymercan be non-cross-linkable (or not cross-linkable under the conditionsused to cross-link the hook-forming polymer), so that it is notnecessary to “mask” the base during cross-linking of the hooks.Alternatively, the hook-forming polymer can be harder than thebase-forming polymer, and both polymers can have the desired propertieswithout cross-linking.

[0034] A suitable process for forming such a two-polymer fastener isshown in FIG. 4. A first extruder 35 extrudes a first, hook-formingpolymer 38 onto mold roll 40, forcing some of the polymer intohook-forming cavities 42 and leaving a layer of polymer on the surfaceof the mold roll. As mold roll 40 rotates in the direction of arrow A,doctoring blade 44 removes some or all of the polymer on the surface ofthe mold roll without disturbing the polymer in cavities 42. The removedpolymer, which has been exposed to air while on the mold roll and mayhave begun to solidify, may be either discarded or returned to thehopper for remelting. The thickness of polymer left on the surface ofthe roll by the doctoring blade will depend, in part, on how close theblade is positioned to the surface of the mold roll (the position isadjustable in the direction indicated by arrow B). In some cases, thesharp, distal end of blade 44 rides against the mold roll, therebyliterally scraping off essentially all of the polymer on the surface ofthe roll. In such cases it is recommended that the end of the blade becoated with a lubricious material to avoid damaging the surface of themold roll. In other cases, the position of the blade is adjusted toleave a predetermined thickness of polymer on the roll, to become a partof the base of the product. In such cases, the doctoring bladeeffectively trims the polymer thickness rather than actually “scraping”against the surface of the roll. Next, a second extruder 47 extrudes asecond, base-forming polymer 50 onto the surface of the mold roll (oronto any of polymer 38 left on the surface of the roll by blade 44). Agear pump 36, 48, is positioned at the outlet of each extruder, toaccurately control the rate of polymer delivered to the mold roll. Thefinal thickness of the base of the product is then adjusted by roll 52,rotating in the direction of arrow C, and the finished fastener product60 is stripped from the mold roll 40 by passing it around exit roll 54.

[0035] For forming a fastener product having a relatively stretchablebase and relatively stiff fastener elements, a urethane may be employedfor the hook-forming polymer 38 and a rubber-filled polyethylene orpolyester based thermoplastic may be employed for the base-formingpolymer 50. An example of such a base-forming material is ARNITEL EM400,available from DSM.

[0036] Examples of various fasteners that can be formed using theprocess shown in FIG. 4 (or modifications of this process) are shown inFIGS. 5-5D.

[0037]FIG. 5 shows a fastener 62, in which the hooks 64 are formed of afirst polymer and the base 66 is formed of a second polymer. Using theprocess shown in FIG. 4, such a fastener can be formed by scrapingsubstantially all of the first polymer off of the surface of the moldroll prior to applying the second polymer.

[0038]FIG. 5A shows a fastener 68, in which the hooks 70 and the upperportion 72 of the base 74 are formed of a first polymer, and the lowerportion 76 of base 74 is formed of a second polymer. Using the processshown in FIG. 4, such a fastener can be formed by adjusting doctoringblade 46 away from the mold roll surface so that a thin layer of thefirst polymer remains on the mold roll surface when the second polymeris applied. When using a stiff first polymer and a flexible orstretchable second polymer, the layer of first polymer is preferablysufficiently thin, as determined by the positioning of the doctoringblade, to enable the rupture of the thin layer of first polymer upon theinitial stretch of the second polymer layer, such as during the initialengagement of a diaper tab. Subsequently, the rigidity of the thin layerof the first polymer does not detract from the stretchability of thebase of the fastener product.

[0039]FIG. 5B shows a fastener 78, in which the hooks 80 are formed of afirst polymer 82 and a second polymer 84, and the base 86 is formed of athird polymer 88. To form this fastener, the process shown in FIG. 4 ismodified so that the first extruder 35 applies an amount of the firstpolymer that only partially fills the mold cavities, and then anotherextruder (not shown in FIG. 4) applies the second hook-forming polymerto completely fill the cavities. The process then continues as shown inFIG. 4, with scraping and application of the base-forming polymer byextruder 47. If the two polymers 82, 84 are not compatible, or do notadhere well to each other, a thin tie layer of adhesive, or a thirdpolymer that adheres well to both polymers 82 and 84, can be appliedbetween polymers 82 and 84. This can be accomplished by replacingextruder 47 with a co-extrusion die, or by other known methods ofapplying tie layers.

[0040]FIG. 5C shows a fastener 90 in which the hooks 92 are formed ofthree different polymers 94, 96, 98. This fastener would be formed in amanner similar to that described below with reference to FIG. 5D, addinga further extruder to apply the third hook-forming polymer. Thisembodiment can provide combinations of properties difficult to obtainwith only two polymers. Alternatively, the middle polymer 96 may be usedas a “tie layer” to bond polymers 94 and 98 if, for example, thesepolymers are incompatible or do not adhere well to each other.

[0041]FIG. 5D shows a fastener 100 in which the base 102 and a lowerportion 104 of hooks 106 are formed of a first polymer, and the upperportion 108 of the hooks is formed of a second polymer. This fastenerwould be formed by the process of FIG. 4, by only partially filling themolding cavities using extruder 35, and then completing the filling ofthe cavities with extruder 47.

[0042]FIGS. 6 and 7 show alternative processes for forming a two-polymerfastener. In the process shown in FIG. 6, the first and second polymersare applied to the mold roll by a coextruder 110. In the process shownin FIG. 7, the hook-forming polymer is applied to the mold roll by anextruder 112, and most of the polymer is scraped from the surface of themold roll by a doctoring blade 114, leaving a thin film of polymer, asdescribed above with reference to FIG. 4. The base-forming polymer 116is then laminated to the thin film of hook-forming polymer while thelatter is still on the mold roll, such as in the nip between the moldroll and roll 118, as shown.

[0043] The hook-carrying base that is formed using any of the processesshown in FIGS. 4, 6 and 7 can be partially cross-linked, if one of thepolymers (preferably the hook-forming polymer) is cross-linkable. If theother polymer is not cross-linkable, or not cross-linkable under thesame conditions, it is not necessary to mask or shield that component.Thus, for example, an electron beam can be directed at the entirefastener (positioned so that it hits at least the portions to becross-linked) at a station (not shown) that is downstream of theprocesses shown in FIGS. 4, 6 and 7. If both polymers have the desiredproperties for a given application without cross-linking, thehook-carrying base formed by the processes shown in FIGS. 4, 6 and 7 canbe used “as-is”, without a further cross-linking step.

[0044] Polymers that are suitable for use in the fasteners shown inFIGS. 5-5D include the above-described cross-linkable polymers, ifcross-linking is used. If cross-linking is not used, suitable polymersfor the relatively hard portions of the fastener include polypropylenes,e.g., PROFAX 7823 polymer, commercially available from Montell USA,Inc., and other relatively hard polymers such as PET and polyamides,e.g., polyamide 6/6 and polyamide 6. Preferably, the relatively hardpolymer has a flexural modulus of at least 80,000, more preferably atleast 120,000 psi. Suitable polymers for the relatively soft portionsinclude vulcanized blends of polypropylene and EPDM, e.g., SANTOPRENEpolymers, commercially available from Advanced Elastomer Systems, Inc.,and other relatively soft polymers such as those commercially availableunder the trade names HYTREL and PEBAX. Preferably, the relatively softpolymer has a flexural modulus of greater than 80,000, more preferablyabout 10,000 to 60,000 psi. It is preferred that the two polymers becompatible, i.e., that they adhere to one another and that they berelatively inert with respect to each other (or, if they are reactive,that such reaction does not have a significant deleterious effect on thedesired properties of the polymers). If they are incompatible, a tielayer can be used to join them, as discussed above.

[0045] Other embodiments are within the claims. For example, while FIG.1 shows loop-engageable, hook-shaped fastener elements, the fastenerelements may be of any desired shape (e.g., mushrooms, loops,multi-directional hooks, or spikes). The touch fastener can also includeother raised structures such as veins, ridges, or rip-stoppingformations, which would preferably be selectively cross-linked with thefastener elements.

[0046] Moreover, while the touch fastener shown in FIG. 1 includes anon-cross-linked base and cross-linked fastener elements, for otherapplications other regions of the fastener are cross-linked andnon-cross-linked.

What is claimed is:
 1. A touch fastener comprising: a sheet-form base portion; and extending outwardly from, and integral with, the base portion, a plurality of molded fastener elements; wherein the fastener comprises a cross-linkable polymer, and wherein a first portion of the fastener is more cross-linked than a second portion of the fastener.
 2. The touch fastener of claim 1 wherein at least some of the fastener elements are cross-linked.
 3. The touch fastener of claim 2 wherein said base portion is not cross-linked.
 4. The touch fastener of claim 3 wherein said fastener elements comprise said cross-linkable polymer and said base portion comprises a non-cross-linkable polymer.
 5. The touch fastener of claim 3 wherein said fastener elements and said base portion comprise said cross-linkable polymer.
 6. The touch fastener of claim 3 wherein said base portion has a flexural modulus of less than about 80,000 psi.
 7. The touch fastener of claim 1 wherein said cross-linkable polymer comprises a thermoplastic elastomer.
 8. The touch fastener of claim 1 formed in a continuous length.
 9. The fastener of claim 1 wherein said fastener elements are hook-shaped.
 10. The fastener of claim 9 wherein said hook-shaped fastener elements are cross-linked.
 11. The fastener of claim 10 wherein said fastener elements have a flexural modulus of at least 80,000 psi.
 12. A method of making a touch fastener, the method comprising: (a) forming a sheet-form base portion from a cross-linkable polymer; (b) forming a plurality of molded fastener elements extending outwardly from and integral with said sheet-form base portion, the molded fastener elements being formed from said cross-linkable polymer; and (c) selectively cross-linking a first portion of the cross-linkable polymer while leaving a second portion of the cross-linkable polymer less cross-linked than said first portion.
 13. The method of claim 12 wherein step (c) is performed with electron beam radiation.
 14. The method of claim 12 wherein said polymer comprises a thermoplastic elastomer.
 15. The method of claim 12 wherein the touch fastener further comprises a non-cross-linkable polymer.
 16. The method of claim 15 wherein substantially all of the cross-linkable polymer is cross-linked.
 17. The method of claim 15 further comprising coextruding said cross-linkable and non-cross-linkable polymers to form a sheet of molten polymer, and, in step (a), forming said touch fastener from said sheet.
 18. The method of claim 12 wherein said touch fastener is formed entirely of a cross-linkable polymer, and a portion of the cross-linkable polymer corresponding to the first portion is selectively cross-linked in step (b).
 19. The method of claim 12 wherein said fastener elements are hook-shaped.
 20. The method of claim 19 wherein said hook-shaped fastener elements are cross-linked during step (b).
 21. The method of claim 20 wherein at least part of said base portion is not cross-linked during step (b).
 22. A method of making a touch fastener, the method comprising: (a) forming a preform product comprising a sheet-form base portion and a plurality of molded fastener elements extending outwardly from and integral with said sheet-form base portion, by (a1) forming a first portion of the preform product from a cross-linkable polymer, and (a2) joining the first portion to a second portion of the preform product formed from a second polymer; and (b) at least partially cross-linking the first cross-linkable polymer of the preform product to form the touch fastener.
 23. A method of making a continuous fastener product having an array of fastener elements extending from a sheet-form base, the method comprising: (a) providing a mold roll defining a plurality of fastener element mold cavities extending into the mold roll from the outer circumferential surface of the mold roll; (b) applying a first polymer to a surface of the mold roll and forcing some of the first polymer into the mold cavities, with some of the first polymer remaining on the surface of the mold roll in the form of a film having thickness; (c) with a doctoring blade, removing at least some of the first polymer remaining on the surface of the mold roll after step (b) from the surface of the mold roll to at least reduce the thickness of the film of the first polymer on the mold roll surface; (d) applying a second polymer to the mold roll, the second polymer being compatible with the first polymer and adhering thereto; (e) solidifying the first polymer in the mold cavities to form fastener elements; and (f) removing the fastener elements from the mold cavities.
 24. The method of claim 23 wherein, in step (c), substantially all of the first polymer that remains on the surface of the mold roll is removed.
 25. The method of claim 23 wherein, after step (c), a portion of the film of first polymer remains on the surface of the mold roll.
 26. The method of claim 23 wherein said first polymer is applied by an extruder.
 27. The method of claim 26 wherein said second polymer is applied by an extruder.
 28. The method of claim 23 wherein said first polymer is cross-linkable, the method further comprising, after step (f), cross-linking said first polymer.
 29. The method of claim 23 wherein said first polymer is relatively harder than said second polymer.
 30. The method of claim 23 wherein said first polymer is relatively stiffer than said second polymer.
 31. The method of claim 23 further comprising, after step (d), bonding a third polymer to said second polymer.
 32. A method of making a continuous fastener product having an array of fastener elements extending from a sheet-form base, the method comprising: (a) providing a mold roll defining a plurality of fastener element mold cavities extending into the mold roll from the outer circumferential surface of the mold roll; (b) applying a first polymer to a surface of the mold roll and forcing some of the first polymer into the mold cavities, with some of the first polymer remaining on the surface of the mold roll in the form of a film having thickness; (c) with a doctoring blade, removing at least some of the first polymer remaining on the surface of the mold roll after step (b) from the surface of the mold roll to at least reduce the thickness of the film of the first polymer on the mold roll surface; (d) applying a tie layer to said mold roll, said tie layer being compatible with said first polymer and adhering thereto; and (e) applying a second polymer to said tie layer.
 33. The method of claim 32 wherein said first and second polymers are different materials.
 34. The method of claim 32 wherein said tie layer comprises an adhesive.
 35. The method of claim 32 wherein said tie layer comprises a polymer. 